Pwr (05P0776) - Furuno FM-8800D Service Manual

5.4.6 PWR (05P0776)

This outputs the voltage of +15 VDC from +24 VDC input power. Each protection
circuit and their functions are as below.
TB1
C1-7
24VDC(+)
L1
TB2
24VDC(-)
FG
PWR
05P0776
OVER VOLTAGE PROTECTION
This protection functions to stop the output when power input is anywhere between +42
to +43 VDC and also functions as an automatic recovery function. This detects voltage
on CR4 and controls power relay: K1 through Q 2 and Q3.
LOW VOLTAGE PROTECTION
This protection functions to stop the power output when the power input is anywhere
between +14 to +15 VDC. Detected voltage is determined by voltage divider(between R
7/9 and R 8) and its voltage is used to control U2. Normally, 300 ms after turning on the
power, level will be "L" and sets U1 to "ON".
RUSH CURRENT PROTESTION
When you turn on the power, K1 will be set to "ON" and then, RC (Remote Control) on
U1 will be set to "ON". Delay of RC terminal will depend on C23 on U2.
Approximately 300 ms after turning on the power, level will change to "L". If you turn
on the power without proper adjustment with RC terminal (RC=L level), rush current
will be discharged into U1 and might burn where K1 is connected. This protection
prevents rush current at the time of inserting RC power by adjusting RC terminal to "L"
level 300 ms after turning on the power.
C8-10 L3
C11,12
L2
CR1
K1
R3
AVR
(+12V)
Q3
Q2
Q1: 2SD1271A
CR2: 02CZ12Y
Fig. 5.4.21 PWR Block Diagram
5-25
U1: CBS2002415
+IN
-IN
AVR
(+12V)
R7,9
R5 Voltage
DET.
CR4
U2: M51958BFP
R8
02CZ39
C23
5.4 Block Description
L4
J1-#1-3
+15V
+Vout
C14,15
J1-#6-8
0V
-Vout
RC
J1-#4
PWR SW P
PWR SW M J1-#5
POWER SW